title: Placental volumes measured by 3-dimensional ultrasonography in normal pregnancies from 12 to 40 weeks' gestation.
abstract: OBJECTIVE
  The purpose of this study was to construct nomograms of placental volumes according to gestational age and estimated fetal weight.
  
  
  METHODS
  From March to November 2007, placental volumes were prospectively measured by ultrasonography in 295 normal pregnancies from 12 to 40 weeks' gestation and correlated with gestational age and estimated fetal weight. Inclusion criteria were healthy women, singleton pregnancies with normal fetal morphologic characteristics on ultrasonography, and confirmed gestational age by first-trimester ultrasonography.
  
  
  RESULTS
  The mean placental volume ranged from 83 cm(3) at 12 weeks to 427.7 cm(3) at 40 weeks. Linear regression yielded the following formula for the expected placental volumes (ePV) according to gestational age (GA): ePV (cm(3)) = -64.68 + 12.31 x GA (r = 0.572; P < .001). Placental volumes also varied according to estimated fetal weight (EFW), and the following mathematical equation was also obtained by linear regression: ePV = 94.19 + 0.09 x EFW (r = 0.505; P < 0.001).
  
  
  CONCLUSIONS
  Nomograms of placental volumes according to gestational age and estimated fetal weight were constructed, generating reference values.
authors.affiliation: Obstetrics Department, Faculty of Medicine, Universidade de São Paulo, São Paulo-SP, Brazil.
authors.forename: Carla Fagundes Silva
authors.initials: CF
authors.lastname: de Paula
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Ruano
authors.forename: Juliana Alvares Duarte Bonini
authors.initials: JA
authors.lastname: Campos
authors.forename: Marcelo
authors.initials: M
authors.lastname: Zugaib
mesh_terms: D005260:Female; D020567:Fetal Weight; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009929:Organ Size; D010920:Placenta / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging*; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*